If greenhouse gas emissions continue to rise at their current rate, melt from the Antarctic Ice Sheet may contribute over 1 metre of sea-level rise by 2100 and over 15 metres of sea-level rise by 2500, according to results from an ice-sheet model published in Nature this week.
Global sea level is known to have been 6-9 metres higher during the Last Interglacial (130,000 to 115,000 years ago), and possibly higher during the Pliocene (about 3 million years ago). Although in both cases the Antarctic Ice Sheet has been implicated as a primary contributor of sea-level rise, using Pliocene and interglacial sea-level values to calibrate ice-sheet models has been challenging.
Robert DeConto and David Pollard use a high-resolution ice-sheet model that takes into account physical processes linking atmospheric warming with ice dynamics - such as rainwater-enhanced fracturing of supporting ice shelves, and collapse of marine-terminating ice cliffs - that is calibrated against Pliocene and Last Interglacial sea-level targets and applied to future greenhouse-gas emission scenarios. They show that, if emissions continue unabated, the Antarctic Ice Sheet has the potential to contribute more than 1 metre of sea-level rise by 2100 and over 15 metres of sea-level rise by 2500. In addition, atmospheric warming will become the dominant driver of ice loss, and prolonged ocean warming will delay ice recovery for thousands of years.
This model also shows that a scenario of strong climate mitigation can radically reduce societal exposure to higher sea levels, with little to no net sea-level change.